Current threats to mussels are tied to their biology – hitchhiking activity and their method of breathing through a tube (siphon). If the host fish cannot migrate upstream due to obstruction or water conditions, the hitchhiking mussel larvae (glochidia) can’t catch a ride. Even though mussels can live a long time, some areas have not had any new mussel hitch a ride for 70 years. And when they can migrate, sometimes they can’t breathe because of cloudy water. Many species have been lost through destruction of their habitat by human alterations to river channels. Most mussels require water that flows over clean, stable sand and gravel.
Another effect of destroying habitats on our major rivers is that populations in tributaries become isolated. Following an impoundment of a river, what was once a single large population of a particular species becomes fragmented into a number of smaller populations, separated from each other by expanses of poor habitat. These smaller populations often lack the genetic diversity to help them overcome changing conditions and are more likely to become locally extinct than larger populations.
But, even though many species have been lost, there are some bright spots. Several areas of good habitat with diverse mussel assemblages remain. A few smaller rivers and streams, such as Sipsey River and many of the streams in Bankhead and Talladega National Forests, have mussel faunas that are basically intact. The Federal Clean Water Act, implemented in 1971, has improved water quality in many rivers, and mussel reintroduction efforts are under way. There are plans to reintroduce some species that have not been seen in Alabama for almost one hundred years.
Enter the mussel whisperer – Dr. Paul Johnson and his team of experts at the Alabama Aquatic Biodiversity Center. The Alabama Aquatic Biodiversity Center, located in Perry County, has the largest non-game recovery program in the nation. Stationed near the Cahaba River and adjacent to the Marion State Fish Hatchery, Perry Lakes Park, and The Nature Conservancy’s Barton’s Beach Preserve, they go beyond aquatic animal research and recovery efforts to promote river recovery and restoration. Several groups are working on improving the migration path of Alabama’s mussels, as well as reintroducing larvae above dam obstructions.
Initially focusing on high conservation priority watersheds such as the Paint Rock and Cahaba Rivers, AABC has released federally endangered Plicate Rocksnail (Leptoxis plicata) into the Locust Fork of the Black Warrior River, north of Birmingham, in Jefferson County. A Black Warrior River basin endemic, the historical 373-square-mile (600-kilometer) range dwindled to about 21 square miles (34 kilometers) as a consequence of dam construction, channelization, and poor water quality.
The Mussel Whisperers can’t do this alone. Almost one half of Alabama’s mussels are considered extinct, threatened, endangered, troubled, or of special concern. Proper management, protection, and monitoring of the surviving native mussel resources (especially habitat) are essential to preserve this biologically diverse group. A strong mussel population reflects a healthy, flowing habitat. Let’s keep our water clear so mussels can still eat through their siphons and keep our channels open so they can still catch a ride with a host fish.